1. Field
The present invention relates to optical communication equipment and, more specifically but not exclusively, to an optical transmission scheme using frequency-diversity (FD) multiple-input/multiple-output (MIMO) signal processing.
2. Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the invention(s). Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Telecommunications companies face continuing demands for increased capacity in their metro, regional, and long-haul optical networks, e.g., due to the proliferation of high-speed data services, video services, and business and residential broadband connections. While optical fiber has a very large intrinsic capacity for transporting data, the spectral efficiency realized in modern optical networks still has significant room for improvement. For example, one of the most spectrally efficient optical-transport techniques employed today is optical orthogonal frequency-division multiplexing (OFDM), which uses modulated subcarriers that are spaced exactly at the baud rate. However, a higher spectral efficiency than that supported by optical OFDM is likely to be required to meet the capacity demands in the future.
In telecommunications and electronics, the term “baud rate” refers to the data rate expressed in the units of symbols per second or pulses per second. Baud rate, also sometimes referred to as “modulation rate,” is therefore the number of distinct symbol changes or signaling events applied to the transmission medium per second using a digitally modulated signal or line code. The corresponding bit rate is a product of the baud rate and the number of bits per symbol in the employed modulation format or constellation.